Camera system for a motor vehicle

ABSTRACT

A camera system for a motor vehicle is described. Incident radiation is guided to a radiation receiving unit by means of one or more deflecting mirrors, where at least one deflecting mirror is configured to swivel. The swivelable deflecting mirror has a first mirror side, which is suitable for deflecting incident radiation, and a second mirror side, which is also suitable for deflecting incident radiation. The second mirror side exhibits a curvature shape that is different from that of the first mirror side. The swivelable deflecting mirror can be oriented in such a manner that incident radiation can be guided to the receiving unit by selecting one of the first or the second mirror side as an effective mirror surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to German PatentApplication No. 10 2006 004260.3 filed Jan. 31, 2006, the entiredisclosure of which is herein expressly incorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a camera system for a motor vehicle, in whichincident radiation is guided to a radiation receiving unit by means ofone or more deflecting mirrors, where at least one deflecting mirror isconfigured so as to swivel.

Modern motor vehicles employ increasingly more camera-based functions.One consideration with respect to such cameras that are used for saidfunctions is to mount the cameras in the motor vehicle in such a mannerthat they are protected and require little space.

For applications in which the radiation, for example visible light orinfrared radiation, is to be received from the direction of travel ofthe motor vehicle, conventional systems include cameras having a lenswhich is also oriented directly in the direction of travel. Therefore,the camera is exposed to the risk of stone impact, moisture and otherenvironmental influences. In addition, the camera occupies a relativelylarge area at the front of the vehicle, a feature that may have anegative effect on the air cooling of the components of the vehicle.When it is necessary that the radiation be received from differentdirections, the entire camera package in such devices is designed sothat it can move. In such devices an optical zoom is possible only withan optical system that is installed in the respective camera.

To increase the freedom to choose an installation site for a camera,camera systems can be used in which a single deflecting mirror or aplurality of deflecting mirrors guide the light. These mirrors serve toguide the incident radiation to the actual receiving unit of the camerasystem. The receiving unit can thus be shifted from the desiredreceiving site, where the incident radiation is to be received. Theincident radiation at the receiving site is guided to the receiving unitby means of the mirror optics. The use of such a mirror optical systemis appropriate especially for camera systems in which there is onlylimited space at the receiving site for mounting the camera system, forexample in the outside mirror of a motor vehicle.

The use of an optical system with mirrors can also guarantee enhancedprotection for the receiving unit of a camera system againstenvironmental influences. Since only a deflecting mirror, and not thereceiving unit itself, has to be oriented in the direction of travel,the receiving unit can be disposed in such a manner that it is protectedagainst direct stone impact and other environmental influences. Usingsuch a system it is also possible to produce a device having a verysmall frontal area, for example only causing an obstruction the size ofthe deflecting mirror at the front of the vehicle. Such a feature yieldsa number of advantages for the air cooling of the vehicle components.

It is known, for example from the DE 10255194 A1, to use swivelabledeflecting mirrors for camera systems in motor vehicles, in order tocover different receiving areas. Thus, a single camera can be used forreceiving radiation from different directions. Only the deflectingmirror has to be swiveled, a feature that is usually realized with lesstechnical complexity than the swiveling of a complete camera package.

Conventional camera systems that use deflecting mirrors exhibit severaldrawbacks. For example, the use of rigid deflecting mirrors offers onlyvery few options for adjusting the optical parameters of the system,such as the aperture angle for receiving the radiation. To eliminatethis drawback, there exist, for example, deflecting mirrors withvariable curvature and/or micro-mirror arrays. However, owing to thehigh cost of materials and production as well as excessive technicalcomplexity, the practical use of such systems in automobiles has beenlimited.

The Exemplary embodiments of the invention provide a simple camerasystem for a motor vehicle, which can be mounted in such a manner thatit occupies little space and is protected from the environment, andwhich also has a variable aperture angle.

According to the invention, a camera system for a motor vehicle isprovided, in which incident radiation is guided to a radiation receivingunit by means of an optical system with one or more deflecting mirrors.At least one deflecting mirror is configured so as to swivel; and the atleast one swivelable deflecting mirror exhibits a first mirror sidewhich is suitable for deflecting incident radiation, and a second mirrorside, which is also suitable for deflecting incident radiation. Thesecond mirror side exhibits a curvature shape that is different fromthat of the first mirror side. The at least one swivelable deflectingmirror is swivelable in such a manner that incident radiation canselectively be guided to the receiving unit by either the first or bythe second mirror side.

Other advantageous embodiments and further developments of the inventionare disclosed in the following.

According to the embodiments of the invention, it is always only eitherthe first or the second mirror side that can be selected to effectivelyact as the deflecting mirror. No expensive mechanism to adapt the shapeof the curvature of a deflecting mirror is necessary. Instead, themirror side acting as the effective deflecting mirror, is simplyalternated between the two sides of the mirror. For example, thedeflecting mirror may be rotated about 180 degrees to switch between thetwo reflective sides thereof.

The invention achieves with very little technical complexity the featurethat the aperture angle of the camera system can be varied, at leastbetween any two sets of characteristics. In addition to a variation ofthe aperture angle, any variation in the optical characteristics thatcan be produced by different shapes of the curvature of the two mirrorsides can be achieved by switching between the two mirror sides. Forexample, the first mirror side may exhibit a symmetrical distortioncharacteristic, while the second mirror side may have an asymmetricaldistortion characteristic.

Additional embodiments of the invention can also include deflectingmirrors with more than two mirror sides and correspondingly more thantwo different shapes of curvature. However, a swivelable deflectingmirror with two mirror sides disposed back to back, which are offsetfrom each other by approximately 180 degrees, can be produced in a verysimple way with little material. The exemplary deflecting mirror can beconstructed substantially flat and with very little weight. In differentembodiments, the assembly may have a configuration with six mirrorsides, for example disposed in the shape of dice.

In one embodiment, the camera system includes a drive mechanism forswiveling at least one swivelable deflecting mirror and a related drivecontrol. The low weight of the deflecting mirror is especiallyadvantageous for dimensioning such a drive.

For example, the at least one swivelable deflecting mirror can beswiveled in such a manner that with a single mirror side radiation fromdifferent directions can be guided to the radiation receiving unit.Therefore a swivel function, to orient the effective deflecting mirrortowards multiple sources of radiation, can also be used in connectionwith the invention. According to an especially preferred embodiment ofthe invention, the at least one swivelable deflecting mirror can berotated about at least two rotational axes, in order to guide theradiation from different directions to the radiation receiving unit witha single mirror side. Thus, for example, the effective deflecting mirrorcan swing along both a horizontal and a vertical translation path.

The exemplary swivelable deflecting mirror can be swiveled about arotational axis in such a manner that the source direction of theradiation, which is guided to the radiation receiving unit by the singleeffective mirror side, can be varied as desired. In addition, the mirrorside that is used as the effective mirror side can be alternated. Inthis way a single drive accomplishes both a swivel function forreceiving the radiation from different directions and a switchingfunction that changes the mirror side that acts as the effectivereflective surface of the deflecting mirror. A drive control to achievethese two functions can be implemented correspondingly with a simpledesign.

The camera system according to the embodiments can be used for a varietyof vehicle functions by using different mirror sides of the deflectingmirror. Similarly, the inventive camera system can be used for variousmodes of a vehicle function by using the different mirror sides of thedeflecting mirror. For example, the first mirror side may be constructedin such a manner that it provides a large effective aperture angle fortaking a picture with the camera system. This feature may be helpful,for example, in monitoring the near environment of the vehicle. Thesecond mirror side may be constructed in such a manner that it providesa small effective aperture angle for taking a picture with the camerasystem, a feature that offers many advantages in monitoring the nearfield over a wide range.

In another embodiment of the invention, the radiation receiving unit maybe suitable for receiving infrared radiation. Specifically, theradiation receiving unit can be suitable for receiving infraredradiation of the near and/or far infrared range. The above-describedbenefits with respect to protection against stone impact, moisture andother environmental influences apply especially to infrared cameras,which are often very expensive. Since infrared cameras are also oftenrelatively bulky compared to other cameras, the invention provides theadditional benefit of a small size, suited to the limited space at thedesired location and promoting the unimpeded air cooling of the vehiclecomponents by covering as little frontal area as possible at the frontof the vehicle.

In embodiments where the receiving unit is suitable for receivinginfrared radiation, the related mirror optical system is also suitablefor guiding the infrared radiation to the receiving unit. Accordingly,the surface of the first mirror side of the deflecting mirror and thesurface of the second mirror side of the deflecting mirror arepreferably suited for reflecting infrared radiation. This requiresspecial materials, such as, for example, high-grade steel and germanium.Consequently, at least the surfaces of the first and the second mirrorside of the deflecting mirror used for infrared applications may be madepreferably of fine-grade steel and/or germanium. To use the respectivematerial economically, the mirror sides of the deflecting mirror may beonly coated with the desired material.

In an exemplary camera system according to the invention, the swivelabledeflecting mirror can be housed both outside the camera package, or maybe housed jointly with the radiation receiving unit inside the camerapackage. In the latter case, owing to the housing of the camera package,the deflecting mirror as well as its mounting and its drive can receivegreater protection against environmental influences.

Other objects, advantages developments and novel features of the presentinvention will become apparent from the following detailed descriptionof the invention when considered in conjunction with the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an exemplary embodiment of a camera system according tothe invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a preferred embodiment of a camerasystem, according to the invention. The camera system 1 includes areceiving unit 3 and a deflecting mirror 4.

The receiving unit 3 is, for example, a remote infrared camera and issuitable for receiving remote infrared radiation. Said unit can be usedin different modes in a night vision system for the purpose of providingassistance to the driver of a motor vehicle. The camera may be disposedtransversely to the direction of travel in a motor vehicle (notillustrated in the drawing). The deflecting mirror 4 receives theinfrared radiation 2 a, which impinges on the deflecting mirror 4 alongthe direction of travel, and reflects it as the infrared radiation 2 b,in the direction of the receiving unit 3 so that the receiving unit 3may receive it.

As shown in the illustration of the top view of the camera system 1, thedirection of travel is to the left. The mirror side 4 a of thedeflecting mirror 4 serves to reflect the incident infrared radiation 2a downward as the reflected radiation 2 b, toward the receiving unit 3.

The deflecting mirror 4 can be swiveled about two axes 5 a and 6 a(projecting outside the drawing plane of FIG. 1). Two drive units (notillustrated in the drawing) and one drive controller operativelyconnected to the two drive units are used to swivel said deflectingmirror 4. The drive controller in turn is operatively connected to thenight vision system for the purpose of assisting the driver. Theinfrared images taken with the receiving unit 3 may be sent to the nightvision system for processing and display.

As shown, rotation about the axis 5 a, which is illustrated by therotating arrow 5 b in FIG. 1, corresponds to a vertical swing of thedeflecting mirror with respect to the motor vehicle. A vertical swingabout the axis 5 a can be executed in an exemplary angular range ofabout +/−15 degrees.

A rotation about the axis 6 a, which is illustrated by the rotatingarrow 6 b in FIG. 1, corresponds to a horizontal swing of the deflectingmirror with respect to the motor vehicle. A horizontal swing about theaxis 6 a can be executed, for example, in an angular range between about−30 degrees and about +210 degrees. Owing to the large angulardeflection range possible in the horizontal swing, the deflecting mirror4 can be rotated by 180 degrees such that the incident infraredradiation 2 a impinges on the mirror side 4 b, not on the mirror side 4a. In this folded configuration, the mirror side 4 b serves to reflectthe incident infrared radiation 2 a in the direction of the receivingunit.

In addition to switching the effectively used mirror side by rotatingthe mirror 4 over the range of 180 degrees, a more reduced angularrotation range of between about −30 degrees and about +30 degrees may beprovided. This reduced rotation range may be used for the purpose ofguiding incident radiation from various horizontal directions to thereceiving unit 3 with a single effective mirror side of the deflectingmirror 4, without switching to the other mirror side.

According to the invention, the two mirror sides 4 a and 4 b exhibitdifferent shapes of curvature. The result of these different shapes ofcurvature is that the effective optical aperture angle of the camerasystem 1 varies. By switching between the two mirror sides 4 a and 4 b,it is possible to realize a change-over between the two differentaperture angles. The two adjustable and different aperture angles areused in two different modes of the aforementioned night vision system.

In the above described embodiment the two mirror sides are alternated,for example, in an advantageous manner by simply swiveling a singlemoveable component, i.e., the deflecting mirror 4. No dedicated driveelement is required to switch between the mirror sides. The same driveelement is used that is also used to guide the radiation from differenthorizontal directions to the receiving unit 3 by rotating a singlemirror side of the deflecting mirror 4.

The night vision system according to the invention may utilizes controlcommands sent to the drive control unit both to switch between the twomirror sides as a function of the respective desired mode, and alsowithin each of the two modes to provide horizontal adjustment in anangular range between about −30 degrees and about +30 degrees as well asa vertical fine adjustment in an angular range of about +/−15 degrees.

The mirror sides 4 a and 4 b of the exemplary deflecting mirror 4 may becoated with germanium. Therefore, incident infrared radiation is largelynot absorbed, but rather reflected.

The foregoing disclosure has been set forth merely to illustrate theinvention and is not intended to be limiting. Since modifications of thedisclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

1. A camera system for a motor vehicle, comprising: an optical systemmounted to the motor vehicle in which incident radiation is guided to aradiation receiving unit, which is oriented facing a directiontransversely related to a direction of travel of the motor vehicle,using at least one swivelable deflecting mirror mounted to a frontalarea of the vehicle, the at least one swivelable deflecting mirrorcomprising a first mirror side suitable for deflecting incidentradiation, and a second mirror side suitable for deflecting incidentradiation, wherein the second mirror side exhibits a curvature shapethat is different from a curvature shape of the first mirror side, andwherein the at least one swivelable deflecting mirror is swivelable insuch a manner that incident radiation can be guided to the receivingunit by swiveling the deflecting mirror to selectively switch betweenthe first and the second mirror sides, wherein the at least oneswivelable deflecting mirror is configured to swivel about at least twoplanes of rotation, and wherein the axes for each of said planes ofrotation pass through the swivelable deflecting mirror, and whereinfurther the at least one swivelable deflecting mirror swivels in one ofthe at least two planes of rotation across an angular range, limited tono more than about +/−15 degrees, in order to reflect radiationoriginating from different directions.
 2. The camera system, as claimedin claim 1, wherein the at least one swivelable deflecting mirrorcomprises two mirror sides.
 3. The camera system, as claimed in claim 1,wherein the at least one swivelable deflecting mirror is orientable suchthat a selected one of the first and second mirror sides reflectsradiation from different directions towards the radiation receivingunit.
 4. The camera system as claimed in claim 1, wherein the at leastone swivelable deflecting mirror is swivelable such that the incidentradiation originating from multiple directions is selectively reflectedto the radiation receiving unit by an effective mirror surface, and suchthat the effective mirror surface is selectable by switching between thefirst and the second mirror sides.
 5. The camera system, as claimed inclaim 1, further comprising a drive of the camera system for swivelingthe at least one swivelable deflecting mirror, and a related drivecontroller.
 6. The camera system, as claimed in claim 1, wherein each ofthe first and second mirror sides of the swivelable deflecting mirror ofthe camera system corresponds to a different vehicle function.
 7. Thecamera system, as claimed in claim 6, wherein the camera system isswitchable between various vehicle functions by switching between thefirst and the second mirror sides of the swivelable deflecting mirror.8. The camera system, as claimed in claim 1, wherein the radiationreceiving unit is suitable for receiving infrared radiation.
 9. Thecamera system, as claimed in claim 1, wherein a surface of the firstmirror side of the deflecting mirror and a surface of the second mirrorside of the deflecting mirror are suitable for reflecting infraredradiation.
 10. The camera system of claim 1, wherein the axes of each ofsaid planes of rotation intersect each other.
 11. The camera system ofaccording to claim 1, wherein the optical system produces an obstructionat the frontal area that is substantially the size of the swivelabledeflecting mirror.
 12. The camera system according to claim 1, whereinthe swivelable deflecting mirror swivels in another of the at least twoplanes of rotation by no more than about +/−30 degrees in order toreflect radiation from different directions.
 13. The camera systemaccording to claim 1, wherein the at least one swivelable deflectingmirror swivels in the one of the at least two planes of rotation acrossthe angular range of no more than about +/−15 degrees as a vertical fineadjustment.
 14. An optical system for reflecting incident radiation,comprising: a swivelable deflecting mirror, mounted to a frontal area ofa motor vehicle, for reflecting the incident radiation towards aradiation receiving unit that is oriented facing a directiontransversely related to a direction of travel of the motor vehicle; afirst mirror side of the swivelable deflecting mirror having firstoptical characteristics; a second mirror side of the swivelabledeflecting mirror having second optical characteristics; and a drivemechanism for selecting an effective reflective surface of theswivelable deflecting mirror by switching between the mirror sides,wherein the at least one swivelable deflecting mirror is configured toswivel about at least two planes of rotation, and wherein the axes foreach of said planes of rotation pass through the swivelable deflectingmirror, and wherein further the drive mechanism's swiveling of theswivelable deflecting mirror in one of the at least two planes ofrotation occurs over an angular range, limited to no more than about+/−15 degrees, in order to reflect radiation originating from differentdirections.
 15. The optical system according to claim 14, wherein theswivelable deflecting mirror swivels no more than about −30 degrees toabout +30 degrees in another of the at least two planes of rotation toreflect the radiation originating from different directions.
 16. Theoptical system according to claim 14, wherein the swivelable deflectingmirror swiveled by about 180 degrees in another of the at least twoplanes of rotation in order to switch the effective mirror surfacebetween the first and the second mirror sides.
 17. The optical systemaccording to claim 14, further comprising additional mirror sides of theswivelable deflecting mirror selectable by the drive mechanism.
 18. Theoptical system according to claim 14, wherein the swivelable deflectingmirror is optimized to reflect infrared radiation.
 19. The opticalsystem according to claim 14, wherein the first mirror side has a firstcurvature, and the second mirror side has a second curvature.
 20. Theoptical system according to claim 14, further comprising a controllerunit of the drive mechanism for commanding a swivel function of theswivelable deflecting mirror to reflect incident radiation fromdifferent directions, and a switching function to select an effectivereflective surface of the swivelable deflecting mirror.
 21. The opticalsystem according to claim 14, wherein the axes of each of said planes ofrotation intersect each other.
 22. The optical system according to claim14, wherein the optical system is configured to produce an obstructionat the frontal area that is substantially the size of the swivelabledeflecting mirror.
 23. The optical system according to claim 14, whereinthe drive mechanism's swiveling of the swivelable deflecting mirror inthe one of the at least two planes of rotation occurs over the angularrange of no more than about +/−15 degrees as a vertical fine adjustment.